Use of catheters to administer fluids to and draw out of the body has been a standard practice in medical procedures for years. Multiple catheters are typically used to connect an extracorporeal circuit to the body during open heart procedures. The various catheters are simultaneously used to provide different functions, one catheter for delivering a cardioplegia solution, with another catheter being inserted into the heart to infuse oxygenated blood to the ascending aorta.
In a typical open heart procedure, blood is bypassed from the heart and lungs to a heart lung machine. When bypassing the heart, the blood is siphoned away from the superior vena cava and inferior vena cava, oxygenated, and then returned to the ascending aorta. The primary reason for using the extracorporeal circuit is to provide an empty and bloodless heart for the surgeon to effectively perform repair. In spite of bypassing the blood from the heart, the heart muscle will still beat, primarily for two reasons. First, the heart muscle is still receiving oxygenated blood from the extracorporeal circuit. Secondly, the heart's electrochemical activity is still functioning normally.
In a typical open heart procedure, the aorta is cannulated in two locations. In a first location, the aorta is cannulated with a first catheter for returning oxygenated blood to the body from the extracorporeal circuit. Oxygenated blood is delivered to the heart with a catheter through the coronary arteries from the base of the aorta, known as the aortic base. To stop the flow of oxygenated blood to the heart, the ascending aorta is typically clamped distal to the coronary ostia, known as the opening for coronary arteries with a large stainless steel aortic cross clamp. Clamping the ascending aorta isolates the coronary arteries from the extracorporeal circuit.
The aorta is cannulated in a second location using a second catheter to deliver cardioplegia. The electrochemical action of the heart can be stopped by infusing the heart muscle with a cardioplegia solution. Cardioplegia solution is typically rich in potassium ions. The potassium ions interrupt the heart's electrical signals, resulting in a still heart. Stopping the heart gives a stable platform to effectively conduct the necessary repairs to the heart. The cardioplegia solution is typically delivered to the heart muscle through the coronary arteries. This is accomplished by infusing the cardioplegia solution into the ascending aorta with the second catheter between the large cross clamp and the aortic valve located at the base of the aorta. The cross clamp keeps the cardioplegia and the oxygenated blood separated from one another.
There are three areas of concern in performing surgery in this conventional, multi-cannulation approach. First, clamping the aorta exerts tremendous force on the aortic walls, and there is a potential for the arteriosclerotic plaque deposits on the aortic walls to dislodge. Due to the proximity of the cross clamp to the carotid artery, this poses a special threat since the dislodged plaque can potentially go straight to the brain, resulting in a stroke to the patient. Secondly, the clamping pressure also causes damage to the delicate endothelial lining of the aorta, which is the inner surface of the artery. Post operative scaring of the endothelial lining can provide an irregular surface causing increased arteriosclerotic plaque build up. Finally, the two cannula suture sites created by the cardioplegia cannula and arterial return cannula tend to scar the aorta and make it very difficult to find suitable cannulation sites for open heart procedures in the future, if necessary.
One prior art method of addressing the short comings of current multicannulation procedures is by percutaneously accessing venous and arterial blood femorally, such as disclosed in U.S. Pat. No. 5,478,309 to Sweeter et al. This method, however, is cumbersome and are dependent on the skill level of the surgeon. Moreover, this percutaneous approach is a major deviation from the conventional methods.
Alternatively, cardioplegia can be delivered through the coronary sinus in conventional ways. Although this alternative approach helps avoid one incision in the aorta, another incision is required in the right atrium, and the aortic clamp is still needed.
There is a desire to provide an improved cardiac catheter for infusing the heart with oxygenated blood and delivering cardioplegia solution in a more atraumatic way.
There is also a desire to provide an improved catheter for occluding a body vessel, such as the aorta, that has a varying diameter and curvature.